This invention relates to surface illuminators of the type employed with video inspection systems, and more particularly to an improved, high-incidence programmable surface illuminator capable of directing collimated light beams onto an inspected workpiece at angles of incidence in the range of approximately 45.degree. to beyond 90.degree..
Heretofore a variety of systems have been developed for illuminating and inspecting workpieces or manufactured parts of various shapes and configurations. Such devices, frequently referred to as surface illuminators, frequently are designed so that the part that is to be inspected is surrounded by one or more light sources which direct illumination obliquely onto the surface or surfaces of the part to be inspected. U.S. Pat. No. 4,893,223, for example, utilizes a plurality of light emitting diodes that are mounted in locations disposed in a segmental spherical array, so that light beams therefrom are directed at different angles of incidence onto the surface of the part to be inspected. A somewhat similar illuminating system is disclosed in U.S. Pat. No. 5,038,258, in which case light modulators are interposed between the sources of light and the part that is being inspected. Moreover, in U.S. Pat. No. 5,690,417, which is owned by the same assignee as the present application, a plurality of light sources in the form of light emitting diodes, or the like are arranged in radially spaced, circular arrays between a Fresnel lens and a workpiece that is to be inspected. As a consequence, collimated beams of light are directed by the Fresnel lens obliquely, and at different angles of incidence onto the part that is being inspected.
While the foregoing illuminator devices are suitable for inspecting certain types of workrjieces, it has been found that there is a need for a surface illuminator which can direct beams of light from an LED array toward a common focus located at the part that is to be inspected, and in such manner that the beams of light are directed at angles of incidence encompassing a range not heretofore possible by prior art devices--namely, providing angles of incidence that range from around 45.degree. to beyond 90.degree..
Accordingly, it is an object of this invention to provide an improved high-incidence, programmable surface illuminator which is capable of directing onto a part that is to be inspected an array of collimated light beams which can be directed onto the workpiece at angles of incidence ranging from around 45.degree. to beyond 90.degree..
A further object of this invention is to provide a surface illuminator of the type described in which an ellipsoidal or concave paraboloidal mirror is utilized to reflect beams of light from an array thereof to a common object plane or focus, and at angles of incidence ranging from around 45.degree. to beyond 90.degree..
Still a further object of this invention is to provide an improved surface illuminator of the type described in which the paraboloidal mirror and object being inspected are capable of being adjusted relative to each other, thereby to alter the range of angles of incidence of the beams that are directed onto the workpiece.
Other objects of the invention will be apparent hereinafter from the specification and from the recital of the appended claims, particularly when read in conjunction with the accompanying drawings.